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	$232.64	9.493%	$254.7245	$254.72	$254.70	$254.70
Purchase #2	$188.84	12.560%	$212.5583	$212.56	$212.55	$212.60
Purchase #3	$105.85	3.320%	$109.3642	$109.36	$109.35	$109.40
Purchase #4	$239.85	3.127%	$247.3501	$247.35	$247.35	$247.40
Purchase #5	$79.29	12.390%	$89.114	$89.11	$89.10	$89.10
Purchase #6	$152.27	6.470%	$162.1219	$162.12	$162.10	$162.10
Purchase #7	$53.63	10.215%	$59.1083	$59.11	$59.10	$59.10
7 purchase totals =	$1,052.37		$1,134.3413	$1,134.33	$1,134.25	$1,134.40