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	$184.27	6.603%	$196.4373	$196.44	$196.45	$196.40
Purchase #2	$62.78	5.721%	$66.3716	$66.37	$66.35	$66.40
Purchase #3	$112.51	11.115%	$125.0155	$125.02	$125.00	$125.00
Purchase #4	$33.68	11.370%	$37.5094	$37.51	$37.50	$37.50
Purchase #5	$98.66	5.662%	$104.2461	$104.25	$104.25	$104.20
Purchase #6	$104.47	9.368%	$114.2567	$114.26	$114.25	$114.30
Purchase #7	$91.55	4.307%	$95.4931	$95.49	$95.50	$95.50
7 purchase totals =	$687.92		$739.3297	$739.34	$739.30	$739.30