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	$196.74	4.427%	$205.4497	$205.45	$205.45	$205.40
Purchase #2	$111.62	11.117%	$124.0288	$124.03	$124.05	$124.00
Purchase #3	$73.80	5.839%	$78.1092	$78.11	$78.10	$78.10
Purchase #4	$62.78	13.817%	$71.4543	$71.45	$71.45	$71.50
Purchase #5	$55.43	10.412%	$61.2014	$61.20	$61.20	$61.20
Purchase #6	$183.33	6.641%	$195.5049	$195.50	$195.50	$195.50
Purchase #7	$184.63	6.594%	$196.8045	$196.80	$196.80	$196.80
7 purchase totals =	$868.33		$932.5528	$932.54	$932.55	$932.50