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	$54.66	4.516%	$57.1284	$57.13	$57.15	$57.10
Purchase #2	$95.65	7.285%	$102.6181	$102.62	$102.60	$102.60
Purchase #3	$250.41	5.600%	$264.433	$264.43	$264.45	$264.40
Purchase #4	$196.62	12.565%	$221.3253	$221.33	$221.35	$221.30
Purchase #5	$128.66	5.647%	$135.9254	$135.93	$135.95	$135.90
Purchase #6	$81.31	5.384%	$85.6877	$85.69	$85.70	$85.70
Purchase #7	$216.85	12.745%	$244.4875	$244.49	$244.50	$244.50
7 purchase totals =	$1,024.16		$1,111.6054	$1,111.62	$1,111.70	$1,111.50