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	$78.76	10.334%	$86.8991	$86.90	$86.90	$86.90
Purchase #2	$19.34	3.684%	$20.0525	$20.05	$20.05	$20.10
Purchase #3	$186.85	5.603%	$197.3192	$197.32	$197.30	$197.30
Purchase #4	$86.44	3.519%	$89.4818	$89.48	$89.50	$89.50
Purchase #5	$231.32	7.760%	$249.2704	$249.27	$249.25	$249.30
Purchase #6	$191.46	3.252%	$197.6863	$197.69	$197.70	$197.70
Purchase #7	$216.44	3.173%	$223.3076	$223.31	$223.30	$223.30
7 purchase totals =	$1,010.61		$1,064.0169	$1,064.02	$1,064.00	$1,064.10