Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$155.62	12.296%	$174.755	$174.76	$174.75	$174.80
Purchase #2	$211.52	5.297%	$222.7242	$222.72	$222.70	$222.70
Purchase #3	$188.52	5.360%	$198.6247	$198.62	$198.60	$198.60
Purchase #4	$159.32	8.120%	$172.2568	$172.26	$172.25	$172.30
Purchase #5	$211.25	12.796%	$238.2816	$238.28	$238.30	$238.30
Purchase #6	$227.96	13.294%	$258.265	$258.27	$258.25	$258.30
Purchase #7	$234.33	6.515%	$249.5966	$249.60	$249.60	$249.60
7 purchase totals =	$1,388.52		$1,514.5039	$1,514.51	$1,514.45	$1,514.60