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	$188.84	7.200%	$202.4365	$202.44	$202.45	$202.40
Purchase #2	$32.49	9.170%	$35.4693	$35.47	$35.45	$35.50
Purchase #3	$236.46	6.632%	$252.142	$252.14	$252.15	$252.10
Purchase #4	$114.58	10.110%	$126.164	$126.16	$126.15	$126.20
Purchase #5	$184.89	3.667%	$191.6699	$191.67	$191.65	$191.70
Purchase #6	$177.77	10.433%	$196.3167	$196.32	$196.30	$196.30
Purchase #7	$122.77	3.777%	$127.407	$127.41	$127.40	$127.40
7 purchase totals =	$1,057.80		$1,131.6054	$1,131.61	$1,131.55	$1,131.60