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	$110.59	3.227%	$114.1587	$114.16	$114.15	$114.20
Purchase #2	$85.48	4.453%	$89.2864	$89.29	$89.30	$89.30
Purchase #3	$245.96	3.784%	$255.2671	$255.27	$255.25	$255.30
Purchase #4	$45.80	4.553%	$47.8853	$47.89	$47.90	$47.90
Purchase #5	$105.37	8.234%	$114.0462	$114.05	$114.05	$114.00
Purchase #6	$173.31	3.110%	$178.6999	$178.70	$178.70	$178.70
Purchase #7	$68.86	4.515%	$71.969	$71.97	$71.95	$72.00
7 purchase totals =	$835.37		$871.3126	$871.33	$871.30	$871.40