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	$199.59	7.142%	$213.8447	$213.84	$213.85	$213.80
Purchase #2	$206.68	7.446%	$222.0694	$222.07	$222.05	$222.10
Purchase #3	$67.44	6.541%	$71.8513	$71.85	$71.85	$71.90
Purchase #4	$161.86	13.223%	$183.2627	$183.26	$183.25	$183.30
Purchase #5	$55.33	6.596%	$58.9796	$58.98	$59.00	$59.00
Purchase #6	$214.70	11.245%	$238.843	$238.84	$238.85	$238.80
Purchase #7	$75.86	8.673%	$82.4393	$82.44	$82.45	$82.40
7 purchase totals =	$981.46		$1,071.2900	$1,071.28	$1,071.30	$1,071.30