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	$196.65	7.133%	$210.677	$210.68	$210.70	$210.70
Purchase #2	$101.30	10.310%	$111.744	$111.74	$111.75	$111.70
Purchase #3	$80.44	13.463%	$91.2696	$91.27	$91.25	$91.30
Purchase #4	$88.46	10.857%	$98.0641	$98.06	$98.05	$98.10
Purchase #5	$180.95	10.593%	$200.118	$200.12	$200.10	$200.10
Purchase #6	$164.65	12.300%	$184.902	$184.90	$184.90	$184.90
Purchase #7	$223.37	9.203%	$243.9267	$243.93	$243.95	$243.90
7 purchase totals =	$1,035.82		$1,140.7014	$1,140.70	$1,140.70	$1,140.70