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	$72.81	4.788%	$76.2961	$76.30	$76.30	$76.30
Purchase #2	$130.33	5.829%	$137.9269	$137.93	$137.95	$137.90
Purchase #3	$30.86	8.739%	$33.5569	$33.56	$33.55	$33.60
Purchase #4	$175.73	11.496%	$195.9319	$195.93	$195.95	$195.90
Purchase #5	$202.56	4.593%	$211.8636	$211.86	$211.85	$211.90
Purchase #6	$215.53	8.277%	$233.3694	$233.37	$233.35	$233.40
Purchase #7	$165.96	8.791%	$180.5495	$180.55	$180.55	$180.50
7 purchase totals =	$993.78		$1,069.4943	$1,069.50	$1,069.50	$1,069.50