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	$195.97	3.298%	$202.4331	$202.43	$202.45	$202.40
Purchase #2	$216.80	5.869%	$229.524	$229.52	$229.50	$229.50
Purchase #3	$227.28	5.816%	$240.4986	$240.50	$240.50	$240.50
Purchase #4	$27.56	8.384%	$29.8706	$29.87	$29.85	$29.90
Purchase #5	$100.33	9.243%	$109.6035	$109.60	$109.60	$109.60
Purchase #6	$56.77	9.737%	$62.2977	$62.30	$62.30	$62.30
Purchase #7	$188.76	11.575%	$210.609	$210.61	$210.60	$210.60
7 purchase totals =	$1,013.47		$1,084.8365	$1,084.83	$1,084.80	$1,084.80