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	$167.63	10.639%	$185.4642	$185.46	$185.45	$185.50
Purchase #2	$71.26	9.686%	$78.1622	$78.16	$78.15	$78.20
Purchase #3	$31.33	10.250%	$34.5413	$34.54	$34.55	$34.50
Purchase #4	$248.34	9.343%	$271.5424	$271.54	$271.55	$271.50
Purchase #5	$22.99	11.753%	$25.692	$25.69	$25.70	$25.70
Purchase #6	$220.86	6.420%	$235.0392	$235.04	$235.05	$235.00
Purchase #7	$174.43	12.689%	$196.5634	$196.56	$196.55	$196.60
7 purchase totals =	$936.84		$1,027.0047	$1,026.99	$1,027.00	$1,027.00