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	$99.65	4.790%	$104.4232	$104.42	$104.40	$104.40
Purchase #2	$155.78	11.373%	$173.4969	$173.50	$173.50	$173.50
Purchase #3	$55.57	11.401%	$61.9055	$61.91	$61.90	$61.90
Purchase #4	$136.40	12.518%	$153.4746	$153.47	$153.45	$153.50
Purchase #5	$179.26	5.345%	$188.8414	$188.84	$188.85	$188.80
Purchase #6	$249.46	8.373%	$270.3473	$270.35	$270.35	$270.30
Purchase #7	$205.44	6.140%	$218.054	$218.05	$218.05	$218.10
7 purchase totals =	$1,081.56		$1,170.5429	$1,170.54	$1,170.50	$1,170.50