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	$212.70	7.360%	$228.3547	$228.35	$228.35	$228.40
Purchase #2	$80.36	13.263%	$91.0181	$91.02	$91.00	$91.00
Purchase #3	$216.95	11.755%	$242.4525	$242.45	$242.45	$242.50
Purchase #4	$91.74	9.146%	$100.1305	$100.13	$100.15	$100.10
Purchase #5	$47.66	9.705%	$52.2854	$52.29	$52.30	$52.30
Purchase #6	$240.66	4.221%	$250.8183	$250.82	$250.80	$250.80
Purchase #7	$191.66	9.238%	$209.3656	$209.37	$209.35	$209.40
7 purchase totals =	$1,081.73		$1,174.4251	$1,174.43	$1,174.40	$1,174.50